Subject: [PATCH] md:change resync_mismatches to atomic64_t to avoid races

Now that multiple threads can handle stripes, it is safer to
use an atomic64_t for resync_mismatches, to avoid update races.

Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index e913356..8034fbd 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1876,7 +1876,7 @@
 		} else
 			j = 0;
 		if (j >= 0)
-			mddev->resync_mismatches += r1_bio->sectors;
+			atomic64_add(r1_bio->sectors, &mddev->resync_mismatches);
 		if (j < 0 || (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)
 			      && test_bit(BIO_UPTODATE, &sbio->bi_flags))) {
 			/* No need to write to this device. */